Portable tool



Nov. 20, 1945. A. G. IMHOF EI'AL PORTABLE TOOL Filed Deb. 15, 1945 2Sheets-Sheet 1 No v. 20, 1945. A. s: IMHOF ET AL 21,389,314

PORTABLE TOOL Filed-Dec. 13, 194s- ZSheets-Shet 2 Patented Nov. 20, 1945PORTABLE TOOL Alfred Godfrey Imhof, London, and Louis Hoyles, Stanmore,England; said Hoyles assignor to said Imhof Application December 13,1943, Serial No. 514,152

' In Great Britain January 27, 1943 8 Claims.

This invention relates to means for facilitating the correct positioningand holding of a portable tool such as an electrically driven drillingmachine, commonly known as an electrically driven drill, or an electricdrill.

According to the present invention we provide a portable tool such as anelectrically driven drilling machine with a guide plate which is adaptedto be pressed against the action of a spring or its equivalent on to thework to be operated on and is connected to the casing .or body in whichthe tool holder is mounted by means of one or more guides of improvedconstruction which constrain the plate to move (relatively tothemachine) in a direction parallel'with the axis of the tool itself.

At least one of the guides is so arranged that the travel thereofcombined with adequate hearing surfaces to maintain the parts in line isgreater than in the case of a simple telescopic arrangement consistingof two parts which are pressed towards their extended position by aspring. This increase in travel is efiected by means of a guide(preferably telescopic) comprising two members provided with a thirdmember which serves to maintain the two members aligned, and isconstrained to move relatively to the two members as the guide isextended or retracted.

In the accompanying drawings which illustrate theinvention:

Figure 1 is an elevation partly in section and Figure 2 is a sectionalplan view;

Figure 3 is a detail view;

Figures 4 and 5 show a modification.

Figure 6 is an elevation partly in section of the arrangement shown inFigure 1 but with parts in a different position.

Referring to Figure 1, l is a portable electrically driven drillingmachine shown in dot and peck lines; I" is an ordinary self-centeringchuck adapted to hold drills or other tools of different diameters.

l I is a casting which is secured to the casing of the machine l bymeans of a screw l2 and guide pins l3 which are reduced in diameter attheir inner ends and screw threaded. I4 is a casting, the outer end ofwhich forms a guide plate and is provided with tubular extensions I5forming guides for the pins 13, and with a tubular extension it whichforms the outer member or tube of the telescopic guide giving a greatertravel than is the case with a simple telescopic guide. I! is the innermember of the telescopic guide and comprises a tube which fits onto aboss IS on the casting l I, and is held thereon by a pin H). as abearing of considerable length to keep the tubes I 6 and I1 coaxial withone another. The tube I1, is a sliding fit on the sleeve 20 and isprovided at its outer end with a peripheral flange 2| which is a slidingfit in the tube Hi. The tube 20 is a floating guide or sleeve whichserves I6 is'provided at its outer end with an internally projectingperipheral flange 22 which is a sliding fit on the tube ll. The sleeve20 is provided with a peripheral flange 23 which is a sliding fit in thetube Hi. 24 is a partition in the sleeve 20. The tube 16 is closed by anend plate 25 which is provided with apertures 26 to allow free ingressand egress of air to and from the tube I6. 21 is a spring locatedbetween the boss 18 and partition 24, and 28 is a spring located betweenthe partition 24 and the end plate 2'5. Normally the tubes t6 and l! ofthe guide are maintained in their extended position by the springs 21and 28, the relative movement between the tubes being limited by theflanges 2| and 22., As the guide is retracted against the action of thesprings 21, 28, the sleeve 20 is also constrained by the springs 21, 28to move relatively to the tubes l6 and 11 until finally in the extremeretracted position the tubes l 6 and H and the sleeve 20 take up theposition shown in Figure 6.

It will be seen that the distance between the boss 18 and the end plate25 in the extended position of the guide is reduced by substantially onehalf when in the retracted position shown in Figure 6 and that at alltimes the tubes l6 and I! are well supported by the sleeveZil. It willalso be seen that with this arrangement if a short drill be employed thetelescopic guide would withdraw it an inconveniently long distance fromthe work. In order to obviate this the outer tube It is provided with anumber of screw threaded holes '29 into any one of which a screw 30 canbe inserted, as shown in Figure 3, which will be engaged by the flange Hon the tube l1 and thereby restrict the outward movement of the guideplate M. In Figure 2 the opening 3| through which the drill I can beseen is provided with three triangular projections 32 which facilitatethe placing of the guide plate. 14 in its proper position to drill.Figures 4 and 5 show an alternative arrangement in which the aperture 3!is screw threaded to receive a bush 33 adapted to fit into holes in a.jig, the bush 33 having a central aperture 34 of appropriate diameterto form a guide for the drill to be used.

In operation the tool is placed in position, the guide plate l4 beingpressed against the work to be drilled so that its surface is in contactwith the surface of the work to be drilled. So long as the guide plateis held in this position, the machine is constrained to move in adirection at right angles to the work.

The guide plate l4 may, if desired, be formed as an electromagnet.

If the work to be drilled is e. g. curved instead of plane the guideplate 14 may obviously be so shaped as to make contact therewith.

Although Figure 1 shows a drilling machine having two telescopic guides(l3, IS) without a guided solely by the telescopic guide, this latterbeing provided with means such as a key and keyway to prevent rotationalmovement between the machine i and the guide plate i4.

It has been found that a portable drilling ma chine fitted with a guideplate according to this invention is particularly suitable for drillingseveral thicknesses of thin material at the same time,

If a jig be used, there-is less wear on the jig (even without the use ofa bush such as is showniat 33 Figure 4) the holes made by the drill arecircular the risk of breakage of the drill is reduced, and there is lesswear on the sides of the drill.

What'we claim is v v 1. In a portable tool, the combination of a toolholder, a guide plate adapted to be pressed against the work to beoperated on by said tool, and at least one guide comprising threemembers slidably mounted relatively to one another, one of the membersserving to maintain the other two members in line'with one another,means constraining the said member to move relatively to the two membersas the guide is extended or retracted, the said guide connecting saidguide plate to said tool, whereby the guide plate is constrained to-movein a direction parallel with the axis of said tool holder, and meanstending to force said guide to its extended position;

2. Ina portable tool, the combination of a tool holder, a guide plate'adapted to be pressed against the work to be operated on by said tool,and at least one guide comprising three tubular members slidably mountedrelatively to oneanother, one of the members serving to maintainthe'other two members coaxialwith one another, means constraining thesaid member to move relatively to the two members as the guide isextended or retracted, the said guide connecting said guide plate tosaid tool, whereby the guide plate is constrained to move in a directionparallel with the axis of said tool holder, and means tending; to forcesaid guide to its extended position.

'3. In'a portable tool, the combination of a tool holder, a guide plateadapted to be'pressed against the work to be operated on by said tool,and at least one guide comprising two tubular members slidably mountedon a sleeve, a partition in said sleeve, and means constraining themembers and sleeve to move/relatively to one another as the guide isextended or retracted, the said guide connecting said guide plate tosaid tool, whereby the guide plate is constrained to move in a directionparallel with the axis of said tool holder and means tending to forcesaid guide to its extended position.

4. In a portable tool, the combination of a tool holder, a guide platehaving an aperture to enable the end of the tool to be seen where itenters the work and adapted to be pressed against the work to beoperated on by said tool, and at least one guide comprising threemembers slidably mounted relatively to one another, one of the membersserving to maintain the other two members in line with one another,means constraining the said member to move relatively to the two membersas the guide is extended or retracted,

, to its extended position.

5. In a portable tool, the combination of a, tool holder, a guide plate,a bush on said guide plate adapted to fit into holes in a jig, saidguide plate .being adapted to be pressed against the work to beoperatedon by said tool and to be positioned by said bush, and at leastone guide comprising two tubular members slidably mounted on a sleeve, a

partition in said sleeve, and means constraining the members and sleeveto move relatively to one another as the guide is extended or retracted,the said guide connecting said guide plate to said tool whereby theguide plate is constrained to move in a direction parallel with the axisof said tool holder, means tending to force said guide to its extendedposition, and means for limiting to various lengths the travel of saidguide.

6. In a portable tool, the combination of a tool holder, a guide plateadapted to be pressed against the work to be operated on by said tool, abush on said guide plate adapted to fit'into holes in a jig, and atleast one guide comprising three members slidably mounted relatively toone another, one of the members serving to maintain the other twomembers in line with oneanother, means constraining the said member tomove relatively to the two members as the guide is extended orretracted, the said guide connecting said guide plate to saidtool,whereby the guide plate is constrained to move in a direction parallelwith the axis of said tool holder, and means tending to force said guideto its extended position.

'7. In a portable tool, the combination of a tool holder, a guide plateadapted to be pressed against the work to be operated on by said tool,

and at least one guide comprising three members slidably mountedrelatively to one another, one

of the members serving to maintain the other two a members in line withone another, means constraining the said member to move relatively tothe two members as the guide is extended or retracted, the said guideconnecting said guide plate to said 'tool, whereby the guide plate isconstrained'to move in a direction parallel with the axis of said toolholder, means tending to force said guide to its extended position, andmeans for limiting to various lengths the travel of the guide platerelatively to the tool.

8. In a'portable tool, the combination of a tool holder, a guide plateadapted to be pressed against the work to be operated on by said tool,and at least one guide comprisingthree tubular members slidably mountedrelatively to one another, one of the members serving to maintain theother two members coaxial with one another,

